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mmcat

mmcat

Note: With any vaguely-modern version of ffmpeg, the following script is made redundant by the concat filter, which achieves the same result in a way that works across platforms. It is a clever workaround of ffmpeg's then-limitations, but most people (i.e. anyone not stuck using an ancient version of ffmpeg for whatever reason) should probably use one of the methods listed in the other article.

The following script can be used to concatenate multiple input media files (containing audio/video streams) into one output file (just like as if all the inputs were played in a playlist, one after another). It is based on this FAQ item: How can I join video files, which also contains other useful information.

If you find any bugs, feel free to correct the script, add yourself to the list of contributors and change the version string to reflect your change(s) or email the author with your patch, whatever you find more convenient.

Instructions

Save the script in a file named mmcat (or some other name), make it executable (chmod +x mmcat) and run it, using the syntax:

./mmcat <input1> <input2> <input3> ... <output>

If you get an error like this:

#/tmp/mcs_v_all: Operation not permitted

that could mean that you don't have correct permissions set on /tmp directory (or whatever you set in TMP variable) or that decoding of your input media has failed for some reason. In this case it would be the best to turn on the logging (as described in the script's comments)

Script

#!/bin/bash

################################################################################
#
# Script name: MultiMedia Concat Script (mmcat)
# Author: burek (burek021@gmail.com)
# License: GNU/GPL, see http://www.gnu.org/copyleft/gpl.html
# Date: 2012-07-14
#
# This script concatenates (joins, merges) several audio/video inputs into one
# final output (just like as if all the inputs were played in a playlist, one
# after another).
#
# All input files must have at least one audio and at least one video stream.
# If not, you can easily add audio silence, using FFmpeg. Just search the
# internet for "ffmpeg add silence".
#
# The script makes use of FFmpeg tool (www.ffmpeg.org) and is free for use under
# the GPL license. The inspiration for this script came from this FAQ item:
# http://ffmpeg.org/faq.html#How-can-I-join-video-files_003f
#
# If you find any bugs, please send me an e-mail so I can fix it.
#
################################################################################
#
# General syntax: mmcat <input1> <input2> <input3> ... <output>
#
# For example: mmcat file1.flv file2.flv output.flv
# would create "output.flv" out of "file1.flv" and "file2.flv".
#
################################################################################

# change this to what you need !!!
EXTRA_OPTIONS='-vcodec libx264 -crf 23 -preset medium -acodec aac -strict experimental -ac 2 -ar 44100 -ab 128k'

################################################################################
#
# NO NEED TO TOUCH ANYTHING AFTER THIS LINE!
#
################################################################################

# the version of the script
VERSION=1.3

# location of temp folder
TMP=/tmp

################################################################################

echo "MultiMedia Concat Script v$VERSION (mmcat) - A script to concatenate multiple multimedia files."
echo "Based on FFmpeg - www.ffmpeg.org"
echo "Don't forget to edit this script and change EXTRA_OPTIONS"
echo ""

################################################################################
# syntax check (has to have at least 3 params: infile1, infile2, outfile
################################################################################
if [ -z $3 ]; then
    echo "Syntax: $0 <input1> <input2> <input3> ... <output>"
    exit 1
fi

################################################################################
# get all the command line parameters, except for the last one, which is output
################################################################################
# $first  - first parameter
# $last   - last parameter (output file)
# $inputs - all the inputs, except the first input, because 1st input is
#           handled separately
################################################################################
first=${@:1:1}
last=${@:$#:1}
len=$(($#-2))
inputs=${@:2:$len}

# remove all previous tmp fifos (if exist)
rm -f $TMP/mcs_*

################################################################################
# decode first input differently, because the video header does not have to be
# kept for each video input, only the header from the first video is needed
################################################################################
mkfifo $TMP/mcs_a1 $TMP/mcs_v1

ffmpeg -y -i $first -vn -f u16le -acodec pcm_s16le -ac 2 -ar 44100 $TMP/mcs_a1 2>/dev/null </dev/null &
ffmpeg -y -i $first -an -f yuv4mpegpipe -vcodec rawvideo $TMP/mcs_v1 2>/dev/null </dev/null &

# if you need to log the output of decoding processes (usually not necessary)
# then replace the "2>/dev/null" in 2 lines above with your log file names, like this:
#ffmpeg -y -i $first -vn -f u16le -acodec pcm_s16le -ac 2 -ar 44100 $TMP/mcs_a1 2>$TMP/log.a.1 </dev/null &
#ffmpeg -y -i $first -an -f yuv4mpegpipe -vcodec rawvideo $TMP/mcs_v1 2>$TMP/log.v.1 </dev/null &

################################################################################
# decode all the other inputs, remove first line of video (header) with tail
# $all_a and $all_v are lists of all a/v fifos, to be used by "cat" later on
################################################################################
all_a=$TMP/mcs_a1
all_v=$TMP/mcs_v1
i=2
for f in $inputs
do
    mkfifo $TMP/mcs_a$i $TMP/mcs_v$i

    ffmpeg -y -i $f -vn -f u16le -acodec pcm_s16le -ac 2 -ar 44100 $TMP/mcs_a$i 2>/dev/null </dev/null &
    { ffmpeg -y -i $f -an -f yuv4mpegpipe -vcodec rawvideo - 2>/dev/null </dev/null | tail -n +2 > $TMP/mcs_v$i ; } &

    # if you need to log the output of decoding processes (usually not necessary)
    # then replace the "2>/dev/null" in 2 lines above with your log file names, like this:
    #ffmpeg -y -i $f -vn -f u16le -acodec pcm_s16le -ac 2 -ar 44100 $TMP/mcs_a$i 2>$TMP/log.a.$i </dev/null &
    #{ ffmpeg -y -i $f -an -f yuv4mpegpipe -vcodec rawvideo - 2>$TMP/log.v.$i </dev/null | tail -n +2 > $TMP/mcs_v$i ; } &

    all_a="$all_a $TMP/mcs_a$i"
    all_v="$all_v $TMP/mcs_v$i"
    let i++
done

################################################################################
# concatenate all raw audio/video inputs into one audio/video
################################################################################
mkfifo $TMP/mcs_a_all
mkfifo $TMP/mcs_v_all
cat $all_a > $TMP/mcs_a_all &
cat $all_v > $TMP/mcs_v_all &

################################################################################
# finally, encode the raw concatenated audio/video into something useful
################################################################################
ffmpeg -f u16le -acodec pcm_s16le -ac 2 -ar 44100 -i $TMP/mcs_a_all \
       -f yuv4mpegpipe -vcodec rawvideo -i $TMP/mcs_v_all \
    $EXTRA_OPTIONS \
    $last

################################################################################
# remove all fifos
################################################################################
rm -f $TMP/mcs_*

The script above can be modified to use the '-f avi' insted of '-f yuv4mpegpipe'. Benefits:

  • unlike yuv4mpegpipe, just one pipe for both video and audio
  • unlike yuv4mpegpipe, matroska and flv, no need to skip header in second file using tail, because avi demuxer will skip it automatically
  • unlike mpegts, avi supports rawvideo and pcm

Pipe-friendly formats

Last modified 10 days ago Last modified on Nov 14, 2017, 9:36:49 PM

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